1. Field of the Invention
The present invention relates to an apparatus and a method for cleaning a substrate, and in particular, to an apparatus and a method for cleaning a substrate which is applicable to a semi-conducter wafer, a glass substrate for a liquid crystal display (LCD) or for a plasma display panel (PDP), etc.
2. Description of the Related Art
Conventionally, a semi-conducter wafer,and a glass substrate for LCD or PDP has been cleaned mechanically or chemically. More specifically, the substrate has been cleaned by utilizing the combination of a brush, which includes a protruded shape made of PVA, etc., with medicinal liquid and the like. In particular, in a case where the substrate is cleaned after a metallic film and an oxidized film are formed on the substrate, or after the substrate is polished chemically and mechanically, the oxidized film can be etched by a great amount of hydrofluoric acid and then cleaned off. However, in most cases, the substrate has been cleaned by a brush. Further, in a case where a resist residue which remains on the substrate is to be removed after it is ashed, the resist is cleaned off by a mixed liqud of sulfuric acid and another medicinal liquid, while on the other hand, in a case where metallic fractions are to be removed from the oxidized film, the metallic fractions are cleaned off by a mixed liquid of hydrochloric acid and another liquid.
The cleaning of the substrate by the brush causes several kinds of problems, for instance, mechanical damage to the substrate, the need to frequently replace the brush due to the fact that the foreign objects which have entered into, or have been entrapped to the brush cannot be completely removed, and the difficulty in adjusting the degree of parallelization of a line formed by tip of the brush against the surface of the wafer.
Further, in a case where the semi-conducter wafer or the glass substrate is to be cleaned by the brush, rubbish, the foreign objects, or particles can be entrapped into the brush to be attached thereto, which results in the incomplete cleaning of the semi-conducter wafer or the glass substrate.
Furthermore, in a case where the semi-conducter wafer or a glass substrate is to be cleaned without using the brush after CMP, there is a problem that the rubbish, foreign objects, and particles can not be completely removed unless it is etched by a large amount of hydrofluoric acid.
In addition, as described above, the resist after it is ashed is removed by a mixed liquid of sulfuric acid and another medicinal liquid, however, it cannot be removed completely through such a chemical reaction. Therefore, it is removed through some processes in each of which a large amount of medicinal liquid is used, which has the disadvantage of increasing the amount of work.